Apparatus for echo distance measurement



Dec. 10, 1946. E. E TURNER, JR 2,412,234

APPARATUS FOR ECHO DISTANCE MEASUREMENT Original Filed Jan. 5, 1940 s Sheets-Sheet 1 l'rwerwor.

COMPR ESSIONAL WAVE PRODUCING DE VICE [aw/1v L. TURNER, JR.

Dec. 10, 1946. E. E. TURNER, JR 2,412,234;

APPARATUS FOR ECHO DISTANCE MEASUREMENT Original Filed Jan. 5, 1940 3 Sheets-Sheet 2 G4 ti-wm e 50 Dec. 19, 1946. R JR 2,412,234

APPARATUS FOR ECHO DISTANCE MEASUREMENT Original Filed Jan. 5, 1940 3 Sheets-Sheet 3 STAGES OF AMPLI FIER lNTERMEDIATE Wflg if I Y Pawnee Dec.10,l946

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star PATENT APPARATUS FOR E MEASUR one ordnance:

Edwin E. Turner, In, West Roxbnry, Mam, as;

signorpby mm amgnments, Signal Company, Boston, Mean,

of Delaware to Submarine a corporation Original application January 5, weasel-m no. 312,50t. Divided and this application November 22, 1940, Serial No. seesaw 2 Claims. (Cl. 177-386) measuring systems and to recording apparatus therefor.

The general principle of echo distance measurement and depth sounding is well known. A compressional wave impulse is transmitted to the water and the reflected signal is received and used to operate an indicator. The time interval between the emitted signal and the received echo is a measure of the distance or depth. This time interval is frequently measured by comparing it with a constant known speed. Thus where a record of th depth is desired, a marking element is usually-moved at a constant speed over a chart, a signal impulse being emitted at the instant the marking point crosses a zero line on the chart and a mark being made on the chart at the instant the echo is received. If the chart be continuously advanced between soundings, the record of the successive periodic measurements will form a graph of the depths traversed. Recording instruments of this type have heretofore been used with more or less success.

The present invention provides, among other things, an improved depth sounding recorder which is particularly adapted for the measurement of both shallow and deeper depths and which, furthermore, produces a record of greater accuracy. It is, moreover, arranged to provide a rugged and serviceable construction.

The various features and objects of the .present invention will best be understood from the following description taken with reference to the accompanying drawings in which Fig. 1 shows a plan view of the record chart and marking element; Fig. 1a, is an end elevation of the marking platen; Fig. 2 is a partial section on line 11-11 of the arrangement shown in Fig. 1 and including also the range-shifting mechanism; Fig. 3 1s a front elevation of the scale-shifting mechanism; Fig. 4 is a section of Fig. 2 taken along the line IV-IV and may be regarded as a back elevation of a portion of the range-shifting mechanism; Fig. 5 is an enlarged cross section of the zero adjustment taken. along the line V-V in .Fig. 3; Fig. 6 is an enlarged plan view of the marking stylus holder; Fig. 'l'is an enlarged section of the same; Fig. 8 is a schematic wiring diagram of the transmitting circuit; Fig. 9 is a schematic wiring diagram of a receiving circult: Fig. 10 is a schematic wiring diagram of a modified receiving circuit providing a sensitvity control; and Fig. 11 is a schematic wiring diagram of a further modification of the receiving circuit providing an automatic sensitivity control.

As shown in Figs. 1 and 2 a chart or record paper I is passed over a platen 2 of conducting material from the roll 3 over an idling roller 4 to a take-up spool 5. The take-up spool 5 may be rotated by suitable gearing, or the like, connected to the motor I or by an independent'rotating mechanism as is well known in the art.

Mounted on a shaft 6 rotated at'a constant speed by motor I is an arm 8 which carries the marking stylus 9. The motor I, while shown for simplicity as being directly connected to the arm 8, may, of course, be coupled to it through suitable gearing if desired. The record paper is preferably of the-type having a conductive carbon back with a thin light-colored coating on its front surface which is removed by the passage of an electric current through the paper. As will more fully appear, the current is passed from the stylus 9 through the paper I to the platen 2. Since the stylus itself is not required to do any work, it is only necessary that it remain lightly in contact with the paper at all times during its passage across the paper. The stylus is therefore in the form of a fine wire which is lightly pressed against the paper. The stylus holder can be seen in Fig. 2 and in the enlarged views of Figs. 6 and '7. The fine wire forming the stylus 9 is passed through a small hole in a cylindrical member ill which is provided with a collar H at the center of'mass of themember iii. A thumb screw l2 passing through the collar and into the member it serves to hold the stylus wire in position. As the marking end of the wire wears away, readjustment can readily-be madeby loosening the screw l2 and pushing the wire 9 farther through the member Hluntil-the desired point is again obtained.

The rotating arm 8 is provided at its end with a block is to which two plates It and I5 are fastened. These are provided with pivots l6 and H which engage the collar II to supportthe styluson the arm 8. A light spring l8 fastened to the bottom end of the stylus holder Ill and to an extension l9 fastened to the block l3 provides the necessary tension to press the stylus against the papera The spring, moreover, serves to make good electrical connection between the stylus and conductor 86,which is connected to a sli rin -8T insulated from the arm and the shaft.

- Inmeasuring shallowdepths-itjis necessary to 3 move the stylus across the chart paper very rapidly. Since the stylus is mounted at the end of the rotating arm 8, the stylus will describe a circle and'will only periodically pass across the paper. In order to avoid any bouncing or chattering of the stylus as it moves across the chart a circular track 28 is provided against which the stylus bears while it is off the paper. 28 is fastened to or made integral with the platen 2. The latter is grooved slightly as shown in Fig. 1a, so that the surface of the paper lies in the same plane or very slightly below the surface of the track 20 and the edges of the platen. By this means the stylus rides onto the paper without any vibration and tearing of the edges of the paper is wholly avoided.

If a signal is. emitted each time the marking,

point crosses the zero line, the maximum depth which can be recorded is that which corresponds to a time of travel of the wave from the ship to the bottom and back equal to the time required for the point 9 to move from the zero line to the line 55 at the opposite edge of the chart. In order to make it possible to use the instrument for deeper depths provision is made whereby the scale represented by the chart can be changed to include different depth ranges.

This involves the transmitting circuit shown in Fig. 8'. A condenser 2| is charged from a source of direct current through a charging resistor 22. When a signal is to be transmitted, the capacitor 2| is discharged through the windings 23 of a compressional wave producing device by the closing of contacts 24 and 25 through the operation of a cam 26 fixed to the rotating shaft 6 which also carries the marker arm 8. Thus a signal will be transmitted once during each revolution the-arm 6. 1

Zero adjustment and range selection are accomplished by varying the position of the contacts 24, 25 with respect to the cam 26 whose position bears a definite relation to the position of the stylus-carrying arm 8. The arrangement is shown in more detail in Figs. 2 to 5.

In the upper part of a frame 21 which may be a portion of the housing of the recorder there is formed a circular aperture concentric with the axis of the shaft 6. The edges of the frame 21 at the aperture are thickened as at 28. The thickened portion is provided with an annular recess into which a flanged plate 29 is fitted. The plate 29 is provided with a central aperture and a recess on its inner side into which the flanged plate 30 is held by a supporting ring 3| and screws 32. The plate 30 carries ball bearing 33 forming the upper support for the end 6' of the shaft 6. The plate 38 is sufilciently loosely fitted into the plate 29 so that the plate 30 is rotatable by means of the knob 34. The plate 30 can, however, be locked in a series of pred termined positions by means'of a pin 45 which is by means of spring 36 pressed into apertures in the plate 38 which are spaced to correspond to the predetermined positions above mentioned. When it is desired to rotate the plate 38 to a, new position, the pin 45 is released by pullin upwards on the knurled knob 31 (Fig. 2). The plate 30 carries the contact mechanism which is best seen in Fig. 4. Contact 25 is fixed to the plate 30 as by the screw 38 and the block 39 which is mountedon the plate 30 by the screw 40. The movable contact 24 is mounted on an arm 4| pivoted at 42.' A spring 43 fixed to the plate 30 by means of the bracket 44 serves to tension the contact 24 against contact 25. The contacts, which are The track suitably insulated from each other, are operated by the cam-follower 46 which is fixed to the arm 4| andwhich bears against the cam 26. The cam 26 may be circular with a flat portion 41 as shown in Fig. 4. When the follower 46 is in contact with the fiat portion 41 of the cam, the contacts 24 and 25 are closed whereas during the remaining portion of the revolution of the cam 26 the contacts remain open. The cam 26 is positioned on the shaft 6 in such a way with respect to the marking arm 8 that a signal is normally transmitted at the instant the marking stylus 9 crosses the zero line on the chart Assuming that the time of travel of the stylus 9 across the chart corresponds to a depth of 55 feet it will be evident that in order to record depths greater than 55 feet the outgoing signal must be emitted prior to the instant at which the stylus 9 crosses the zero line. A second depth range of, say, 35 to feet may, therefore, be chosen. The outgoing signal is produced at the proper instant for this purpose by rotating the plate 38 by means of the knob 34 carrying the contact assembly through an angle equal to the angle traversed by the stylus 9 between the zero and 35 foot lines on the chart. The cam follower 46 is thereby rotated with respect to the cam 26 so that the outgoing signal will be produced at the proper instant.

Other depth ranges can be provided in a similar manner, the contact position being shifted with respect to the cam as predetermined by the location of the holes in the plate 38 which are engaged by the pin 45. The knob 34 may also serve as a pointer to indicate the depth range selected, the ranges being engraved on the plate 29 as shown in Fig. 3.

In order to provide a zero adjustment the plate 29 has a plurality of teeth 48 cut in a portion of its periphery, the teeth being engaged by a pinion 49 whose shaft 50 is driven by a gear 52 and a worm 5| which is rotatable by the knob 53. This arrangement is best shown in Figs. 4 and 5. The worm 5| and gear .52 are mounted in a housing 54 which is fixed to the frame or case 21 of the instrument.

Fig. 9 shows the receiving circuit for causing the returning echo to produce a mark on the record paper. A compressional wave receiver having a voltage generating coil 56 is schematically indicated at 51. The coil 56 is connected to the primary winding 58 of an amplifier input transformer 59 having a secondary winding 68. The output of the secondary 68, shunted by the tuning condenser 6|, is impressed upon the grids 62 and 63 of amplifier tubes 64 and 65, respectively, connected in push pull. The cathodes 66 and 61 of these tubes are grounded through resistor 58 and capacitor 69. The anodes 10 and 1| of the two tubes are connected through intermediate amplifier stages to the grids 14 and 15 of the last stage indicated at 12 and 13. In each stage the cathodes are grounded through a resistor and capacitor as in the case of the first stage. The anodes 16 and 11 are connected across the primary 18 of the output transformer 19. The anodes are provided with a potential by means of the center tap, connection 68 on the primary 18 which is connected to the positive terminal of the plate supply source, the negative terminal being grounded. One end of the secondary winding 8| of the output transformer is connected to the marking stylus 9, the other terminal bein connected through the Push button type normally closed switch 62 to ground.

the paper I and the platen 2 whic is grounded.

It will be noted that a portion of the output potential from the secondary 8| is fed back by means of ,the lead 83 to the common terminal of two series connected capacitors 84 and 95 shunted across the secondary 60 of the input transformer. By this means it is possible by depressing the push button 82 and thereby opening the secondary to ground circuit to throw the amplifier into oscillation and thereby to cause the stylus to make a mark continuously across the paper. Such marks (often called fix marks) are useful in hydrographic survey work where it is often desired to indicate the precise moment at which the survey vessel leaves a known position. The push-pull amplifier not only provides an amplifier of very high sensitivity and gain but also provides a great freedom from stray signals. Furthermore, it makes possible the simple arrangement just described for making "fix" marks without causing any instability in the amplifier.

A modification of the receiving amplifier circuit is shown in Fig, 10. The amplifier as shown in this figure is substantially the same and similar parts have been given the same reference numerals as that shown in Fig. 9. However, the

secondary of the input transformer here numbered 59' is formed of two separate windings 93 and 94 and the secondary of the output transformer here numbered 19' has in addition to the stylus operating winding 8|v a center-tapped winding 89 across which are connected two similar series-connected variable potentiometertype resistors 90 and 9|. The common terminal of the resistors is connected to the center tap of the winding 89, the connection being grounded at 92. The variable contacts of resistors 90 and 9| which are operated in unison are connected. respectively, to the two windings 93 and 94 oi the input transformer. By this means a variable negative feed-back is provided which controls the amplifier sensitivity and sharpness of the tuning. This modification provides a sensitivity control which simultaneously reduces the sharpness of the tuning' of the amplifier, thereby broadening its resonance curve with decrease in sensitivity. Therefore, for shallow depths where .the echo impulse is of relatively high intensity sufficient voltage will nevertheless be built up to operate the indicator here shown as the marking stylus. However, due to the broadening of the amplifier resonance curve the time re quired for the amplifier to build up to a suflicient potential to operate the indicator is reduced. Consequently the error which the amplifiers time delay otherwise introduces into the measurement is considerably reduced. Although this error is relatively small, it becomes of importance where very small depths are to be measured.

It will readily be understood by those skilled in the art that this variable negative teed-back arrangement can be used to provide a sensitivity control for single-sided amplifiers as wellas for the push-pull amplifier here shown. It can also obviously be applied to other types of indicators in addition to the recording stylus herein shown.

A further modification of the receiving circuit is shown in Fig. 11. In this arrangement an automatic sensitivity control is provided which automatically varies the sensitivity in accordance with the length of time interval being measured. In this figure the amplifier is indicated at 95, only the output circuit of the last stage being shown.

The output transformer 96 hasone of its secondary 9'! connected to the recorder stylus 9. The other terminal of the secondary 91 is con nected to ground through a capacitor 98. The latter is maintained in a discharged state by the contact of the stylus 9 with the plate 2 or the track 20 which in this case may bemade of a conducting material. When the stylus 8 travels on to the surface of the record paper I, the capaci-= tor 98 gradually becomes charged by the battery 99 which is in series with the resistance I99. The other terminal of the resistor I90 is connected to one side of the capacitor 98, .the remaining terminals of both capacitor and battery -being connected to ground as indicated. The polarity of th battery is so-arranged that the potential across'the condenser which is in series with the secondary 91 will aid the signal impulse potential in providing enough potential tocause the stylus.

but the condenser 98 will provide an increasingly large potential in aid of the echo impulse potential.

It will be understood that this arrangement can also be applied to other types of indicators, for example, to an electric discharge tube indicator provided that .suitablemeans are supplied for discharging the condenser-99 prior to each time interval measurement. This can readily be accomplished by a simple contact connected to the timing mechanism.

Having now described my invention, I claim:

1. In a recorder for echo distance measuring systems having a record paper, a stylus and means moving the same repeatedly across the paper at a constant speed, means for varying the range of distances recorded on said paper including contact means adapted, when operated, to

eflect production oi a signal impulse, cam means for operating said ,contacts, said cam being mounted on an axis rotated at a speed proportional to the speed of said stylus moving means, a

panel havinga substantially circular aperture therein positioned with its center on said axis extended, a ring rotatably mounted on said panel in said aperture, a circular plate adapted to fit into said ring, means rotatably mounting said plate in said ring, means mounting said contact means fixedly on said plate and positioned to be operated by said cam, manually operable means for rotating said plate within said ring and thereby rotating said contact means relatively to said cam, means for locking said plate in said ring in a plurality of predetermined positions each corresponding to a range of distances to be recorded and independently manually operable means for rotating said ring in said panel and thereby said plate and contact means for providing accurate synchronization between the instant of production of the signal and the instant the stylus crosses a predetermined line on the record paper.

2. In arecorder for echo distance measuring systems having a record paper, a stylus and means moving the same repeatedly across the paper at a constant speed, means for varying the range of distances recorded on said paper including contact means adapted, when oper- I 7 ated, to effect production 0! a signal impulse, cam means for operating said contacts. said'cam being mounted on an axis rotated at a speed proportional to the speed of said stylus moving means, a panel having a substantially circular apertu e therein positioned with its center on said axis extended, a ring rotatably mounted on said panel in said aperture, a circular plate adapted to fit into said ring, means rotatably mounting said plate in said ring, means mounting said contact means fixedly on said plate and positioned to be operated by said cam, manually operablevmeans for rotating said plate within said v ring and thereby rotating said contact means relatively to said cam, means for locking said of distances to be recorded and independently manually operable means. for rotating said ring in said panel and thereby said plate and contact means for providing accurate synchronization between the instant of production of the signal and the instant the stylus crosses a predetermined iine on the record paper comprising a plurality of gear teeth out in a segment of the periphery of said ring and a rotatable worm gear mounted on said panel and adapted to engage said teeth on said ring. I

EDWIN E. TURNER, JR. 

